The present invention relates generally as indicated to a foundry molding machine and method and more particularly to machines providing a parting plane squeeze to achieve uniform high mold hardness over essentially the entire pattern plate face of the mold, while being able to produce such molds at a high production rate with minimal energy requirements.
Conventional foundry mold making machines either of the blow-fill or dump-fill type normally produce a foundry mold having the requisite mold hardness in the center of the flask area, but not necessarily over the entire area of the flask at the pattern. This then limits the configuration of the pattern or the number of patterns which may be utilized in a given pattern plate thus greatly restricting the productivity of the molding system. For example, in some molding machines, a pattern configuration cannot be placed closer than three to five inches from the edge of the flask because of mold hardness problems.
Efforts have been made to alleviate these problems with the use of complex squeeze heads or heads which employ movable portions which apply greater pressure and more squeeze to areas of the mold having greater depth. Also, jolt machines have widely been used to attempt to alleviate these problems. Jolt machines, while in most cases effective, are expensive to build, expensive to maintain, and create a noise environment which is not desirable. Moreover, providing a jolt normally lengthens the cycle of the machine particularly if incorporated with a subsequent squeeze.
Even in blow-squeeze molding machines, the blow operation is normally utilized to pre-compact the sand and this must generally be accomplished under fairly high air pressures such as 50 to 60 psi. Again, such machines normally provide the high mold hardness required only in the center of the mold but not completely to the edge of the flask thus greatly restricting the productivity which may be achieved with a given mold. Moreover, blow-squeeze molding machines operating at such pressures require substantial amounts of energy and are more costly. For example, seals and their maintenance problems may be avoided at much lower pressures. Further, such lower pressures require smaller valves and of course the energy required to operate such valves. Thus not only smaller but fewer valves need be employed. Also, the lower air pressures in a blow operation do not create nearly the sand, dust or dirt problems normally associated with high pressure blow-squeeze machines.
For these reasons it is desirable to provide a foundry molding machine of the blow-squeeze type which can operate at quite low air pressures. It is also desirable to provide such machine which can, with a short cycle time, produce a foundry mold which has high uniform hardness across the entire pattern plate face with an extremely short and energy efficient machine cycle.